Once you have a
Flickr account you may choose to publish your work. When publishing there are 4 main conditions that can be combined to create 6 Creative Commons licenses that you may choose from ranging from accommodating to more restrictive.
Conditions
Attribution
by
"You let others copy, distribute, display, and perform your copyrighted work — and derivative works based upon it — but only if they give credit the way you request."
Share Alike sa
"You allow others to distribute derivative works only under a license identical to the license that governs your work."
Non-Commercial
nc
"You let others copy, distribute, display, and perform your work — and derivative works based upon it — but for non-commercial purposes only."
No Derivative Works
nd
"You let others copy, distribute, display, and perform only verbatim copies of your work, not derivative works based upon it."
Creative Commons Licenses
Attribution 
cc by
This is the least restrictive of the licenses. By applying this license to your work you are allowing people to reproduce and build upon your work on their websites, twitter accounts, and in other commercial uses as long as credit is given for the original work.
Attribution Share Alike cc by-sa
Like the previous license, people may reproduce and build upon your work as long as they credit you and license their creations under the identical terms. This license is more restrictive than the previous because all creations based off your work must be license the exact same way.
Attribution No Derivatives
cc by-nd
Unlike the previous two licenses applying this license to your work allows only for the redistribution of your work with credit given. Under this license no changes can be made to your work.
Attribution Non-Commercial
cc by-nc
This license is similar to the first license in that people can distribute and build upon your work, however it can not be distributed for commercial use. Credit must be given, but the license does not have to be the same.
Attribution Non-Commercial Share Alike
cc by-nc-sa
This license is exactly like the attribution non-commercial license, however any new creations must be licensed the same as the original creation.
Attribution Non-Commercial No Derivatives
cc by-nc-nd
This is the most restrictive license. People may redistribute your work as long as credit is given. However, they can not use the work commercially or adapt it.